By IndiaHub 
Under the new rule, authorised agents will not be allowed to book Tatkal tickets during the first 30 minutes of the booking window on the day Tatkal bookings open.
The rule applies as follows:
For AC classes: Agents cannot book tickets between 10:00 AM and 10:30 AM.
Individuals can book tickets from 10:00 AM. For non-AC classes, agents cannot book tickets between 11:00 AM and 11:30 AM and individuals can book tatkal train tickets from 11:00 AM.